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Help. What steel to use?

Smokey_MattUK

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Joined Mar 23, 2021
Hey all

so I need to pick your brains regarding steel choices.

Steel choices
so I’ve been in contact with several steel suppliers here in the uk and I’ve been able to source 1/4” steel.

Black Mild Steel Sheet

But now I’m being offered black mild steel sheet, which as I understand is hot rolled. And this is the steel produced by the mills prior to undergoing cold rolling.

I’ve not come across this and I’m assured that the melting point is 1400 deg F. So with some welding and treatment it’ll hold up well in the smoker. And combo grill. Even the firebox. But then again I’ve sourced a chap who has some 10mm tube that I’m awaiting on a quote for fabrication.
Question is have you guys come across black steel sheet before and do you think it’s suitable for the bbq smoker??

Reinforced structural elements

second point as well. I’m going to reinforced the straight sides of my drum with an additional layer of 3mm steel.

Chimney Replacement

Part of the reason for doing this is to provide additional support for the replacement chimney I’ve got coming, as I’m going to grind off the current and install a new one that’s 3” diameter by 27” length. I just don’t have good airflow with the current one which is far too small.

I’m curious as to what you think about installing a curved liner out of3mm sheet in the base and welded in place?? Perhaps daveomak daveomak could help here??

firebox design

I’ve included an image of the pipe. It works a charm as it’s 16” diameter which is exactly what I need.Also my sketch up plans are attached if you don’t mind taking a look. I’m currently writing out a spec for the fabricator as well.
lastly, you can see on the pictures the air vent, the cross bar is going to come off and the firebox welded in place. Then also welded to the legs and the crossbar will be welded under that. I may need to weld a couple of supports as well, but I’ll see when it arrives.
Thanks for your input everyone.
 

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bill1

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Joined Apr 25, 2015
Perhaps a minority opinion but I'd say reinforcing steel with added thickness is just an invitation for rust formation. Use as is for a decade or so and then weld on more when rust gradually takes what you already have.
If you're worried about buckling occurring from loading on/off a truck, I'd replace the steel wheels with pneumatic tires to deal with that.
 

Smokey_MattUK

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Joined Mar 23, 2021
Perhaps a minority opinion but I'd say reinforcing steel with added thickness is just an invitation for rust formation. Use as is for a decade or so and then weld on more when rust gradually takes what you already have.
If you're worried about buckling occurring from loading on/off a truck, I'd replace the steel wheels with pneumatic tires to deal with that.
Hey, thanks for that. The image of the firebox is just for reference.
i just have a horizontal drum smoker. No wheels and the steel is probably 2mm thick. So I’m modifying the structure by adding a bigger and longer chimney, but as I’m concerned about the weight of the chimney so reinforcing the steel by inserting an internal support of a full diameter 3mm steel plate.
 

bill1

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Joined Apr 25, 2015
I see your point. The right angle exhaust you have now (~2" ??) uses the natural reinforcement that's on the barrel head due to your use of the stock bung hole. If you drill it out to 3 or 4" you'll lose that. So maybe don't rush into that....
Now in normal plumbing, adding two feet at any diameter adds pressure drop and slows your flow. And esp with liquids, going vertical means you're fighting gravity and that makes pressure drop even worse. But the wonder of draft with heated air is that you'll flow more with that added vertical height. Places like Home Depot sells flat sheets of steel that are intended to be rolled into round ventilation ducting. You could try adapting something like that to what you have and see if 2-3 foot of that doesn't give you the draft/flow you desire. You could also come out small (using what you have) and then step up to a bigger diameter....there's no need this exhaust pipe has to be heavy gauge steel.
Another option could be rectangular metal downspout...if you roll an end round with piece of pipe (like rolling a car fender with a baseball bat) you can probably adapt pretty easily to what you have...some metal band clamps could prove useful...and that stuff is really cheap in 8' lengths. It may not look like a $1000 smoker but it might work quite well!
 

Smokey_MattUK

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Joined Mar 23, 2021
I see your point. The right angle exhaust you have now (~2" ??) uses the natural reinforcement that's on the barrel head due to your use of the stock bung hole. If you drill it out to 3 or 4" you'll lose that. So maybe don't rush into that....
Now in normal plumbing, adding two feet at any diameter adds pressure drop and slows your flow. And esp with liquids, going vertical means you're fighting gravity and that makes pressure drop even worse. But the wonder of draft with heated air is that you'll flow more with that added vertical height. Places like Home Depot sells flat sheets of steel that are intended to be rolled into round ventilation ducting. You could try adapting something like that to what you have and see if 2-3 foot of that doesn't give you the draft/flow you desire. You could also come out small (using what you have) and then step up to a bigger diameter....there's no need this exhaust pipe has to be heavy gauge steel.
Another option could be rectangular metal downspout...if you roll an end round with piece of pipe (like rolling a car fender with a baseball bat) you can probably adapt pretty easily to what you have...some metal band clamps could prove useful...and that stuff is really cheap in 8' lengths. It may not look like a $1000 smoker but it might work quite well!
Yea, I see your point.
I’ve measured the opening internally and the hole itself is actually 3” in diameter, but the fabricator screwed tubing in and installed a 2” pipe. And it’s 10” in length.

when I calculated the draft flow required and the dimensions of the stack if I leave it at 2” then I need like a 90” stack. I’m plucking figures out of the air, but it was a ridiculous length.
By expanding the diameter to 3” I can get away with a 27” stack. Can’t go wider than that internally owing to the warming grate/upper shelf getting in the way.
 

bill1

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Joined Apr 25, 2015
... if I leave it at 2” then I need like a 90” stack...By expanding the diameter to 3” I can get away with a 27” stack...
Yeah, but what if you come out in 2", then step up to 3", either right after your existing 2" miter or include a new 3" miter and cut the 2" right after you come out the end? I suspect the biggest downside is you'll have to scrape out creosote in that narrow iris every half dozen cooks or so.
 

Smokey_MattUK

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Joined Mar 23, 2021
Yeah, but what if you come out in 2", then step up to 3", either right after your existing 2" miter or include a new 3" miter and cut the 2" right after you come out the end? I suspect the biggest downside is you'll have to scrape out creosote in that narrow iris every half dozen cooks or so.
Surely that would apply for a dirty fire??
 

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